Radio frequency (RF) devices, such as cell phone transmitters, are becoming increasingly complex due to requirements to operate according to different modes of operation associated with, for example, additional frequency bands, more complex modulation schemes, higher modulation bandwidths, and the introduction of data throughput improvement schemes such as simultaneous RF transmission and/or reception within a same or different, but closely spaced, bands or channels within a band (e.g. voice, data), and aggregate transmission wherein information is multiplexed over parallel RF transmissions.
In order to achieve a required power output, amplifiers used in such RF devices may include a multi-stage arrangement of amplifiers wherein one or more of such amplifiers may be configured as a cascode amplifier comprising a plurality of stacked transistors in series connection. Such combination of a multi-stage arrangement of amplifiers with inclusion of one or more cascode amplifiers may affect output impedances of the different amplifier stages of the multi-stage arrangement and in turn produce impedance mismatches that can affect performance of the amplifier, such as, for example, output return loss and a voltage standing wave ratio (VSWR) performance.
It is therefore an object of the present disclosure to provide a solution to such impedance mismatch while reducing a performance degradation associated with the provided solution.